Don't reinstall packages that already exist

bin/grin-install.lua

@@ -15,16 +15,24 @@ if not options.package then
 end
 
 local user, repo, tag = grin.packageNameComponents(options.package)
+if grin.isPackageInstalled(grin.combine(user, repo, tag)) then
+    print("Package already installed")
+    return
+end
 
 local releaseInfo = grin.getReleaseInfoFromGithub(grin.combine(user, repo))
 local release
-for i,v in ipairs(releaseInfo) do
-    if v.tag_name == tag then
-        release = v
-        break
+if tag then
+    for i,v in ipairs(releaseInfo) do
+        if v.tag_name == tag then
+            release = v
+            break
+        end
     end
+    assert(release, "Tag not found " .. tag)
+else
+    release = assert(releaseInfo[1], "No releases found")
 end
-assert(release, "Tag not found " .. tag)
 
 local grinPrg = grin.resolveInPackage("ElvishJerricco/Grin", "grin")
 shell.run(grinPrg, "-u", user, "-r", repo, "-t", release.tag_name,

lib/grin

@@ -182,7 +182,8 @@ function getLatestInstalledVersion(pkg)
     expect("string", pkg)
     local jsonData = getReleaseInfo(pkg)
 
-    local user, repo, tag = packageNameComponents(pkg)
+    local _,_, user, repo = pkg:find("^([^/]+)/([^/]+)$")
+    assert(user and repo, "Invalid package name: " .. pkg)
     local packageDir = combine(grinDir, "packages", user, repo)
     for i,v in ipairs(jsonData) do
         if fs.isDir(combine(packageDir, v.tag_name)) then
@@ -207,6 +208,16 @@ function forEach(func)
     end
 end
 
+function isPackageInstalled(pkg)
+    expect("string", pkg)
+    local user, repo, tag = packageNameComponents(pkg)
+    if not tag then
+        return false
+    else
+        return fs.isDir(combine(grinDir, "packages", user, repo, tag))
+    end
+end
+
 local packageAPIs = {}
 function getPackageAPI(pkg, name)
     expect("string", pkg)